Energy exists freely in nature. Some of them exist infinitely (never run out, called RENEWABLE), the rest have finite amounts (they took millions of years to form, and will run out one day, called NON-RENEWABLE)

With this in mind, it is a lot easier to lay any type of energy source in its right place. Let's look at these types of energy in the diagram below:

You will notice that water, wind, sun and biomass (vegetation) are all available naturally and were not formed. The others do not exist by themselves, they were formed. Renewable energy resources are always available to be tapped, and will not run out. This is why some people call it Green Energy.TIPApproximately 20% of electricity produced globally in 2009 came from renewable sources. Out of this, hydro-power accounted for about 16%.

In 2012, 9% of the energy consumed in the USA came from renewable sources. This means the USA depends a lot on non-renewable sources. 30% of the energy from renewable sources came from hydropower, whiles biomass, biofuels and wood, together accounted for about 49%. —Source: USEIA, Monthly Energy Review, April 2013

Illustration of Global Renewable Energy Usage.

When can energy be called 'Renewable'?When its source cannot run out (like the sun) or can easily be replaced (like wood, as we can plant trees to use for energy)When their sources are carbon neutral. This means they do not produce Carbon compounds (such as other greenhouse gases).When they do not pollute the environment (air, land or water)

Renewable energy includes Biomass, Wind, Hydro-power, Geothermal and Solar sources. Renewable energy can be converted to electricity, which is stored and transported to our homes for use. In this lesson, we shall take a closer look at how renewable energy is converted into electricity.